This small business innovation research Phase I project will be used to demonstrate the feasibility of developing a reversible sensor to measure carbon monoxide at very low levels (5 parts per million or lower) where existing devices fail. Aside from the elderly population, carbon monoxide is especially dangerous (even at low levels) for unborn babies, infants, and children who are at much greater risk from exposure because they have smaller bodies, faster metabolisms, and they absorb carbon monoxide quicker. When a fetus is exposed to carbon monoxide, the toxic gas destroys vital oxygen cells, interfering with the brain's development - the organ that require the most oxygen. According to experts, toxic levels of carbon monoxide can be up to ten times higher in the fetus than the mother. In this project innovative indicator formulations will be incorporated as thin film on optical substrates. The Phase I working model will be tested for a variety of performance parameters including sensitivity, response time, accuracy, precision, resolution and interferences. [unreadable] [unreadable]